The present invention relates to a retention and release mechanism for ski boots, and, more particularly, relates to a mechanism and ski boot construction which allows for a safe and biomechanically natural rearward articulation of a user""s foot for thereby substantially reducing the risk of severe injury.
There is an inherent and known risk of injury associated with the sport of downhill skiing. A significant source of injury is the rigid association between a user and prior art skis and ski boots. In view of this, various prior art devices have been proposed for reducing the risk of injury in the sport of downhill skiing. The vast majority of these disclosures relate to improvements in the ski binding, i.e. the mechanism affixed directly to the ski for receiving the ski boot.
In addition, there have been attempts to modify the ski boot itself. Generally, however, ski boot modifications have been directed to providing a mechanism for the wearer to more readily step into and out of the boot. For example, in U.S. Pat. No. 5,136,794 there is reported a ski boot consisting of a lower part and of a shaft, in the form of a collar, which is articulated on the lower part and provided with at least one closing buckle. The shaft includes, at the rear, a rocker that interacts with a stop that is integral with the lower part in order to lock the shaft in a position inclined forwards. The rocker is held in inactive position upon opening of the uppermost buckle by means of a cable and a spring. Thus, the shaft is not inadvertently locked during walking.
Attention is also directed to U.S. Pat. No. 5,127,171 and art cited therein, which reports a ski boot with a shell having a shaft in two parts, the rear part of which is connected, on the one hand, to the shell and, on the other hand, to the front part of the shaft by two pair of links. The axes of articulation on the rear part are situated, in the closed position of the boot, on the sides of the plane containing the axes of articulation on the shaft and the front part of the shaft. It is possible to open the shaft wide for putting the boot on, while having only a limited rearward tilting of the rear part. The upper connection can be associated with a closing lever.
In U.S. Pat. No. 5,107,608, there is reported a ski boot for reducing the incidence of knee injuries wherein the boot is said to exert a forward directional force on the skier""s leg. A releasing means changes the rigid support position for the foot and the lower leg on application of a predetermined level of force by the boot on the wearer. The ""608 patent further reports that rearward pressure of the person""s lower leg against the rear leg element of the boot can be sensed by force sensors producing electrical outputs by the use of piezoelectric material. In addition, as illustrated in FIG. 7 therein, a mechanical latch assembly employing a tension spring is disclosed. The tension spring is described as urging or maintaining the device in ski position, and, when spring force is overcome, a release position is obtained as shown in FIG. 8.
U.S. Pat. No. 5,283,964 discloses a boot device for front-to-back immobilization of the upper, which acts on an oscillating level capable of being supported against a stop on the shell base. The device is constituted by a rectilinear motion control mechanism. The mechanism includes an external control device having an inner part which actuates, via a cam, a sensing device associated with the oscillating lever, thereby imparting to the latter an angular rotating movement around its pin toward a locked or release position in relation to the stop formed on the shell base.
Attention is also directed to following foreign patent documents: WO 92/05718 and 0514762A2. More specifically, in WO 92/05718 there is disclosed a ski boot for enhancing the safety of skiing. Finally, reference is made to EP-375-604-A, which discloses a ski boot with a stop holding the leg forward, and French Patent 2647-649-A, which discloses a ski boot with an articulated leg locked in a forward position. The leg has a clip at the back that pivots around the horizontal axis.
All of the above, however, are distinct from the present invention, in that they collectively fail to provide, in the boot itself, a practical and effective mechanism for mitigation of knee injuries while used in skiing. There is, therefore, a long-felt need in the art for a ski boot retention and release mechanism that specifically reduces potentially injurious forces to the anterior cruciate knee ligament (ACL).
Accordingly, it is an object of the invention to provide a ski boot design that restricts the rearward movement of the rigid upper of a ski boot by allowing rearward travel of the same after a selected level or predetermined threshold of force has been obtained.
Another object of the invention is to provide a ski boot design having a mechanism to affect upper displacement when appropriate to create a safer environment and enhanced safety to the user.
Yet another object of the invention is to provide a ski boot design having a retention and release mechanism to for improving safety.
Another object of the invention is to provide a ski boot that allows the potentially damaging rearward forces at the upper section of a ski boot to be absorbed or transduced.
A further object of the invention is to provide a ski boot design which prevents or mitigates the severity of injuries to the anterior cruciate knee ligament and to provide a more safe natural biomechanical rearward articulation in the boot for the user thereof.
A further object of the invention is to provide a ski boot with a walk position combined with a release mechanism to improve safety.
Yet a further object of the present invention to provide ski boot design which prevents or mitigates the severity of injuries to the anterior cruciate knee ligament that can be cost-effectively mass produced.
These and other objects of the present invention will become apparent from a review of the description provided below.
The present invention is organized about the concept of providing a ski boot having a retention and release mechanism for mitigating injury to the skier""s anterior cruciate knee ligament when the skier exerts rearward loads, potentially injurious to the knee, to the boot shaft upper. The mechanism extends between the lower portion of the ski boot and the upper portion of the boot, which is pivotable with respect to the lower portion. In a xe2x80x9cskixe2x80x9d position, the mechanism maintains stable orientation between the upper and lower portions of the boot. Upon imposition of a predetermined level of rearward force, i.e. in the event of a rearward fall, the mechanism moves to a xe2x80x9creleasexe2x80x9d position wherein rearward rotation of the upper relative to the lower portion is allowed to reduce the risk of injury.
Recovery from the xe2x80x9creleasexe2x80x9d position to the xe2x80x9cskixe2x80x9d position is possible via user stance adjustment in the boot to impart a forward force on the upper. In the event that such a stance adjustment cannot be immediately achieved, the mechanism reduces the moment arm of the ski with respect to the skiers"" center of gravity thereby reducing forces to the knee while still providing support of the leg and thereby permitting the skier to continue skiing until recovery or falling. In the case of falling, rearward contact with the snow over the ski tail requires less derangement and force loading of the knee joint. The mechanism is releasable from the ski boot to allow free rotation of the upper relative to the lower in a xe2x80x9cwalkxe2x80x9d position to facilitate a relatively natural walking motion.
More particularly, a ski boot consistent with the invention includes: a rigid first boot portion pivotally coupled to a rigid second boot portion, and a release and retention mechanism consistent with the invention. The mechanism includes a first linkage having an end coupled to the first boot portion, and a second linkage coupled to the first linkage through a pin disposed in a slot in the first linkage. The mechanism changes the first boot portion from a ski position relative to the second boot portion to a substantially vertical release position upon travel of the pin in the slot due to application of a predetermined rearward force to the first boot portion.